Mantle for incandescent lamps.



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W. H. A. .SIEVERTS.

Application med-Hay 20, 1899.)

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(No Model.)

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UNtTED STATES PATENT OFFICE.

WILHELM HEINRICH AUG. SIEVERTS, OF HAMBURG, GERMANY@ MANTLE FOR INCANDEsoE'NT LAM Ps. y

SPECIFICATION formingpart of Letters Patent N o. 6.60.932, dated October 30, 1900.

Apvplcaton'iiled May 20, 1899. Serial l\lo. 717,592. L'No model-' To all whom zit may concern:

Beit known that 'L'WILHELM HEINRICH AUGUST SIEvERTs, teacher, a subject of the Emperor of Germany, vresiding at Hamburg- Uhlenhorst, in theEmpire of Germany, have invented au Improvedl Mantle for Incandescent Lamps, of which the following is a specication.

This invention relates to mantles for incandescent lamps; and it has for its object to provide a new and improved mantle which is more elastic than the ordinary mantle, is strengthened ina novel manner at the part which usually bears or rubs' against the burner, and at other parts, if desired, the meshes are enabled to slide one inkt-lie other prior to burning to obtain elasticity, the mantle possesses a high coefficient expansion and rapidly expands when lighted, and the illuminating power of the mantle is materially increased. This object is accomplished in the manner and by the means hereinafter described and claimed, reference being made to the accompanying drawings, in which- Figure 1 shows a mantle strengthened by thicker meshes saturated with a thicker coating at the portion between a and o where it may come into contact with the burner. Fig. 2 shows a portion of the weaving of the mautle provided with thick mesh extending from c to d. Fig. 3 shows a ni'antle drawn inwardly by the action of the Haine and which touches the edge of the burner at a d. Fig. 4 shows a mantle constructed in accordance with this invention, as shown separately in Fig. l, mounted upon a Bunsen burner. Fig. 5 shows a mantle constructed in accordance with this invention which is strengthened by thicker meshes and a thicker coating by saturation at its upper end between e andf, at its middle portion between g and h, and at the portion surrounding the burner between t' and 7c.

The object of the invention is to produce a mantle for incandescence which (a) forms an elastic instead of a rigid body as heretofore and (b) is strengthened in the vicinity of the top edge of the burner, so as to enable the mantle to resist the sucking action of the flame, together with the outer pressure of the air, and (c) is formed with a convex portion tain extent.

at the top edge of the burner, so as to prea vent it coming into'contact therewith.

Careful study in the manufacture of incandescent mantles has led yme to discover that, first, the finished mantle has a strong high coefficient expansion, and thus when being lighted it rapidly expands'forseveral millimeters, while shrinking again on being extinguished, and, second',vr the incandescent mantle loses much of its rigidity by a repeated steeping ot' the fabricbefore burning it, inasmuch as the meshes are thereby enabled to slide the one in the other to a cer- The phenomenon mentioned under'No. l is thereason that the slight-lytbuilt and rigid weaving forming the mantle is drawn in bythe sucking action ofthe flame and by the pressure of the air-current which passes through the meshes into the flame, and so comes into contact with the top edge of the burner, as indicated at a d in Fig. 3 of the drawings, and is thus damaged or breaks at that point. The peculiar movement of the meshes mentioned under No. 2 was entirely unknown heretofore and may be explained as being a consequence of the immediate burning of the mantle after a second steeping of the zone which it is desired to strengthen. 'Ihe4 reason for the phenomenon is deduced from the well-known fact that when a small piece of thorium nitrate is placed in a flame it becomes puffed up to a large'extent, owing to the escape of the nitric acid therefrom. By steeping the fabric in strong solution and then burning the Woven fabric before it has time to dry completely a portion of the dissolved thorium nitrate separates before it can be fixed by the fabric and appears thereon in the form ofV minute white pearls. The nitric acid which escapes therefrom causes these pearls to puff up, and thereby prevents t the sintering together of the thorium sucked up by the threads and keeps it perfectly free (not sintered together) at the points of intersection of the burned-out skeleton. The knowledge thus gained from these facts has led to the discovery of an incandescent mantle which by an extra amount of steeping in strong solution is rendered elastic, and thereby vmore able to withstand vibrations and which is further constructed with an out- Wardly-curved zone of thicker meshes at the part surrounding the top edge of the burner in order to prevent it being damaged by coming into contact with the top of the said burners. The strong solution is prevented from spreading beyond the Zone by capillary action either by quickly drying the part or by burning it immediately. A mantle thus treated when placed over the gas-liame bulges out by itself by reason of the remaining or non-treated portion of the mantle shrinking to a greater extent than that of the zonewhich has been dipped in the strong solution.

Any known means may be utilized for producing stronger threads at the desired part of aimantle. Thus, for instance, the `spun threads may be more twisted at someplaces than at others. Such threads enable acylindrical or hose fabric to bemanufacturedhavinglat certain part-s thick zineshes, such as shown at d, Fig. 2. This is then cut to the desired length for `the mantles, `which are thereupon treated inthe well-known manner.

Another disadvantage in connection .with the existing mantles is that they contract at the top aftershort service, and this contraction detracts greatly from the illuminaling power of the mantle, owing to the surface beu ing reducedthereby and the mantle beingvno longer at the periphery of the tlame. Thisis also due to the sucking of the flame, and it may be avoided by forming a strengthening Zone q 7L, Fig. 5, parallel to the one near the top of the burner by meshes of greater thickness and a thicker coating by saturation, as before described. It is also advantageous to strengthen the top portion ortop edge of the mantle, as shown at ef, Fig. 5.

Man tles thus constructed keep their form, and thus retain their illuminating power for a longer period, While the increased deposif tion of materials at the portions most aected by the i'lame `gives `greater brilliancy in the light.

What I claim is As an improved article of manufacture, an elastic mantle offa single layer of Wovennlateria-l `having a Zone formed ot' threads of greater thickness than the threads composing the'body of the mantle, said thickened zone being more heavily coated with incandescing material than, and .with the same incandescing material as, the other Y.portions of the mantle, substantially as described andwforthe purpose specified.

In testimonyiwhereof 1I have hereuntoset myhand, in presence of twosubscribingwitnesses, this .()th day of May, `1899.

WILHELM HEINRICH AUG. ySIIWEIt'lS.

Witnesses:

WILHELM FRENL JULIUs HAND. 

